A storage system in which controllers for controlling access between a host and storage areas are multiplexed is known as a clustered storage system. With this type of storage system, in order to effectively operate a plurality of controllers, the processor of a certain controller must access hardware resources such as a main memory and an interface of another controller. Therefore, in order to make this access rapid and reliable, the processor does not directly access the hardware, rather, the processor gains access via a dedicated LSI for access. As storage systems which comprise clustered controllers, the storage systems disclosed in Japanese Published Patent No. 3719976 and Japanese Published Unexamined Application No. 2008-269424 are known.